1. Field of the Invention
The present invention relates to a polymer material with treated fillers and articles and methods of using same. Particularly, the present invention is directed to the use of treated filler materials in the manufacture of polymer composite foams, to be formed or molded into packaging or consumer products having enhanced properties.
2. Description of Related Art
Packaging structures such as boxes, containers, trays, cups, dinnerware and the like, are formed from a variety of thermoplastic and thermosetting polymers. Mineral fillers are used extensively to enhance the performance of a wide range of such polymers. It is well known that the improvement in the properties of polymers can occur with the proper use of well-dispersed fillers possessing high aspect ratios and small particle sizes. Physical properties of the polymer that can be improved by the use of such fillers include stiffness, strength, temperature resistance, dimensional stability, surface hardness and scratch resistance. Other properties that can be improved with the use of well-dispersed fillers possessing high aspect ratios and small particle sizes include clarity, chemical resistance, flame retardancy, rheological properties, and crystallinity. Such fillers can also be used to reduce permeability to gases and liquids, thereby improving the barrier property of the polymer.
The most commonly used fillers in plastics are calcium carbonate, wollastonite, silica and the phyllosilicates such as kaolin, talc and mica. Many fillers, such as calcium carbonate, silica and phyllosilicates, however, are hydrophilic and therefore must be surface treated in order to improve their dispersion and interaction with the polymer matrix.
Conventional surface treatment of fillers includes reacting the filler surfaces with organosilanes, modified oligomers and polymers containing anhydride functional groups and a wide variety of surfactants. More recently, it has been determined that the exfoliation and nanoscale dispersion of small amounts of treated fillers into polymers results in composite materials with enhanced physical features and significant reductions in weight as compared to polymers with conventional or non-treated fillers. Nanocomposites are a new class of composites that are particle-filled polymers for which at least one dimension of the dispersed filler is in the nanometer range (10−9 meter).
Various methods are known in the art for creating composites with modified fillers which are exfoliated and dispersed in a polymer matrix. Under current methods known in the art, large quantities of volatile polar surfactants are required to ensure complete exfoliation, intercalation or delamination of fillers. There thus remains a need for enhancing the properties of polymer composite foams through the use of treated fillers, particularly, fillers that do not require large quantities of surfactants.